Test System and Methodology
We utilize a new approach to RAID storage testing with our Enterprise Test Bench that is designed specifically to target long-term performance with a high level of granularity. Many testing methods record peak and average measurements during the test period. These average values give a basic understanding of performance, but fall short in providing the clearest possible view of I/O Quality of Service (QoS).
'Average' results do little to indicate the performance variability experienced during actual deployment. The degree of variability is especially pertinent because many applications can hang or lag as they wait for I/O requests to complete. This testing methodology illustrates performance variability and includes average measurements during the measurement window.
All storage solutions deliver variable levels of performance while executing a workload. Providing ongoing measurements from our workloads with one-second reporting intervals illustrates product differentiation in relation to I/O QoS. Scatter charts give readers a basic understanding of I/O latency distribution without directly observing numerous graphs.
The first page of results will provide the 'key' to understanding and interpreting our new test methodology. In replicated environments, RAID 0 can be a compelling choice for bleeding edge performance. RAID 5 provides a layer of data security that protects from the loss of a drive.
We are testing both RAID 0 and RAID 5 in this evaluation. This evaluation consists of tests with default settings conducted on an LSI 9271-8i with a direct connection. We conduct our tests over the full LBA range to allow the HDD to highlight its average performance. Short stroking can increase performance at the loss of capacity.